1. Field of the Invention
The present invention relates to a semiconductor memory device, and more particularly to a Multi-Chip Package (MCP) type semiconductor memory device including a plurality of memory chips and one memory controller chip which are provided in one package.
2. Description of the Related Art
In the field of mobile devices such as mobile phones, advanced functions, such as functions to store and reproduce still images, moving images, and music, and a game function, have been increasingly adopted and there has also been a great demand for high speed processing of a large amount of data. Thus, there is a need to increase storage capacity while achieving a reduction in the size of the semiconductor memory. MCP, which incorporates a plurality of memory chips into one package, is a package technology developed to meet such a need. Particularly, a stack MCP including a stack of two or more chips is effective in reducing package size.
Japanese Patent Kokai Nos. 2006-351664 (Patent Literature 1) and 2001-217383 (Patent Literature 2) describe an MCP type memory system including a plurality of memory chips stacked on a substrate and a memory controller chip provided at one side of the memory chips.
In the semiconductor memory device field, there has been a great demand for a reduction in package size and thickness in addition to demand for increased storage capacity. A configuration in which a plurality of memory chips is stacked and a memory controller chip is then stacked on the stack of memory chips may be considered as a solution to reduce the horizontal size of the package. However, in this case, it is difficult to cope with demand for reduction in the thickness of the package. Thus, there is no choice but to adopt the configuration in which the stacked memory chips and the memory controller chip are mounted side by side as shown in FIG. 8 of Patent Literature 1 and in FIG. 15 of Patent Literature. However, employing this configuration causes an increase in the horizontal size of the package such that it is difficult to meet the demand for reduction in the size of the package.